Various methods have been proposed to separate a semiconductor wafer on which semiconductor integrated circuits are formed and transfer the separated semiconductor integrated circuit chips. By way of example, described in Patent Document 1 is a method for separating integrated circuit chips by performing a so-called trench etching on spaces between the integrated circuit chips by using a dry etching method. Further, described in Patent Document 2 is a chip separation method by which it is possible to divide a wafer by an etching process even in case that chips having irregular shapes when viewed from the top are formed on the wafer.